Directional radio system



April 27, 1943. w. P. LEAR -DIRECTIONAL RADIO SYSTEM Filed Dec. 28, 1940 2 Sheets-Sheet 1,

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ATTORNEY April 27, 1943. w. P. LEAR 2,317,922

DIRECTIONAL RADIO SYSTEM Filed Dec. 28, 1940 2 Sheets-Sheet 2 ATTORNEY Patented Apr. 27, 1943 UNETEB STATES FFEQE 6 Claims.

This invention relates to radio direction finding systems and more particularly to automatic radio direction indicators, being a continuationin-p'art of my copending application Automatic radio direction indicator, Serial No 286,733, filed on July 27, 1939, now Patent No. 2,308,521, issued Jan. 19, 1943 and assigned to the same assignee.

The automatic radio direction finder to which this invention relates employs a reversible electric motor controlled by the received radio signals for rotating a directional antenna into hearing relationship with the incoming radio 'waves. The directional antenna is generally ,a rotatable loop mounted on the. exterior of the aircraft for eflicient signal reception. A 360 indicator is mechanically coupled to the driven directional antenna to indicate its angularpositionand azimuthal bearing.

In accordance withthe present invention, the control motor is arranged remote from the directional antenna, being incorporated in the electrical control compartment. 'As will be set forth indetail hereinafter, locating the control motor within a shielded-chassis close to its electrical control circuits, eliminates the prior electrical cables and thereby electrical interferences with signal reception or the magnetic compass. The

interference generally was manifest as switching clicks and commutator noise, or other electromagnetic waves radiated bythe connecting cable. Furthermore, the motor is subjected to far less variation in temperature than when located adjacent the externally mounted loop antenna as heretofore. The result is a more stable operation.

Another important feature of .the present inbcdiment thereof, illustrated in the accompanying drawings, in which:

Fig. 1 is a diagrammatic illustration of the system, in perspective, showing coaction of the components.

Fig. 2 is a front elevational view' showing the loop" drive unit on the chassis.

Fig.3 is a side elevational'view of the mounted loop control drive and motor.

Fig. 4 is a rear elevational view of the loop motor socket and connections.

Fig. 5 is a side elevational view, partly in section, of the loop control motor of the invention. Fig.6 is an end view of the motor of Fig. 5. The automatic radio directional system, diagrammatically shown in Fig, 1, comprises'a con- 7 trol unit In, a radio and electrical control circuit unit l5, and rotatable directional antenna 20. Antenna 20 is a rotatably mounted loop within streamline housing 2! supported on neck 22. The antenna assembly is arranged on shell 23 of the aircraft, extending above or below the aircraft fuselage to insure efiicient pick-up of the radio signals. The control unit or head I0 is placed near the pilot for remotely operating the direction finder system.

Chassis unit l5 contains the requisite radio and control circuits for the system, being generally located remote from the loop antenna, at a convenient accessible place for its maintenance and servicing. Patent No. 2,308,521 referred to hereinabove discloses appropriate circuits for effecting the automatic radio directional operation.

' A 3609 indicator 25 is coupled to the direction vention resides in the novel construction of the 7 loop control motor. A'pronged plug-in construction is incorporated with the motor at its base, for readily mounting it in position as well as effecting its electrical connection with the circuits. The plug-in construction greatly simplifies servicing and maintenance of the motor inthe field. Since this control motor is an important unit that is checked at regular servicing intervals,

the arrangement of the inventionleliminates costly and time consuming operations required heretofore. The whole motor drive assembly in-- eluding an integral electromagnetic clutch "is readily dismounted and disconnected from its circuit simply by removing a few mounting screws.

These and other advantages, capabilities, and features of the invention will appear from the following detailed description of a specific emquency operation.

finder system, being placed near the pilot for in dicating the bearing position of loop 20. A-band selector switch.30 is provided on control head ID for adjusting the radio circuits in units l0 and I5 tothe desired band of radio fre- Selector switch 30 simultaneously shifts shutter mask 3! of radio tuning indicator 32 in correspondence with the band selected. Details of this arrangement appear in my copending application, Serial No. 378,490, entitled Radio tuningmechanism filed on Feb. 12,

1941. Tuning knob 33 operates a slide-rule type frequency scale 34 to indicate the, frequency of the radio station tuned-in opposite stationary index 35. Tuning knob 33 at the same time rotates mechanical cable 36 coupled to the variable radio frequency condenser bank within chassis unit l5 for correspondingly tuning the contained direction finder circuits. A tuning meter 31, in circuit with the radio system, apprises the pilot of the optimum tuning conditions, The mode of ing 62, 63.

:ircuit operation for the direction finder system .s controlled by switch lever 38 of control head Ill. The gain level of the system is adjusted by mob 39. The electrical connections between control head l and chassis unit 15 comprise junction box 40 and electrical cables 4|, 42.

Chassis unit l5 obtains a removable metallic casing 43 and front panel 44. Reference is directed to my copending application Serial No. 354,653, filed on August 29, 1940, now Patent No. 2,309,323 issued Jan. 26, 1943, for preferred construction of this unit. The non-directional antenna 45 is connected to insulated terminal 46 on the front of unit l5. The master on-ofi switch 41 for the direction finder system is arranged on panel 44, remotely from control head H). The power supply for the system is conducted through cables 42 and 48 via junction box 40.. In this manner, the relatively high amperage current for the system does not pass through the aircraft or adjacent the instrument panel, avoiding any effects on the magnetic compass.

The loop winding 20 is of low impedance, and electrically connected to radio circuit unit l5 by low impedance shielded cable 43 through junction box 45 and cable 42. Connection between cable 49 and the rotatable loop antenna is afforded through slip rings. A quadrantal error corrector unit 50 is coupled between the rotatable loop antenna 20 and mechanical shaft 5| which operates the loop, in a manner such as indicated in my copending application, Serial No. 344,854, filed on July 11, 1940, and assigned to the same assignee.

Loop drive shaft 5| is directly coupled to a drive unit 52 mounted on panel 44 of chassis azimuthal bearing positions of the loop. The

quadrantal error corrector unit 50 automatically compensates the bearing indications for extraneous radio distortions, in a manner well known in the art.

Another feature of the invention resides in arranging a plurality of indicators for the bearing positions. Besides indicator 25, there is the second indicator unit 65, containing a radio bearing index 66. Index 66 is connected to H-coupling unit 55 through mechanical shaft 61. Indicator 65 coaxially coordinates the radio bearing indications with those of a gyro-compass within unit 65, in the manner disclosed in my copending application Serial No. 314,672 filed on January 19, 1940, and assigned to the same assignee. A gear ring supports index 66 and engages with a pinion at 68 in the ratio equal to the gearing between loop antenna 20 and drive shaft 5|, for in-phase driving therewith by shaft 61. The respective mechanical transmission shafts 5|, 53, 60 and ill are individually removably coupled to H-unit 55 through coupling nipples 69. It is to be under-" stood that additional mechanical coupling units may be connected to drive shaft 53 or to any of the individual mechanical drive shafts, for oper-. ating additional remote indicators of the loop bearing positions.

The 360 quadrantal error corrector 50 provided between loop antenna 20 and the plurality of v bearing indicators and motor drive unit 52 affords unit l5, by flexible shaft 53 and shaft 54 of an the control chassis unit l5, remote from the ro-' tatable loop antenna 20. The motor is electrically shielded by housing 43. The cable connections to the motor are short and direct, and

wholly within unit l5. No motor circuit connections are nequired between control unit l5 and the remotely positioned loop 20, thereby avoiding Shaft 53 is removably couinterference with the magnetic compass, or with v the radio reception. Radiation of clicking and commutator noises is eliminated.

I The loop antenna 28 is directly mechanically driven by drive unit 52 through flexible mechanical shafting 5!, 53 joined at H-coupling unit 55. Bearing indicator 25 is mechanically coupled to the mechanical loop drive system by flexible shaft ,6!) connected with shaft 6| of H-unit 55. Shafts 54 and 6! of H-unit 55 are connected by 1.21 gear- Indicator shaftfill is accordingly positively related with motor drive shaft 53, following in phase with shaft 5i that controls the angular position of loop antenna 20. Pointer 64 of indi-- cator 25 is directly geared to 'shaft in the the accurate azimuthal bearing indications at a plurality of positions on the aircraft. The, indicators are thus individually interchangeable or removable, without affecting the operation of the remaining indicators. Coupling nipples 69 of H-unit 55 permit the convenient addition of an indicator if only one has been installed. Furthermore, when remote motor drive unit 52 is dissembled for servicing, the several indicators, 25 and 36, remain in-phase relation with the loop antenna 20 and corrector 53, and need not be tested or readjusted after the servicing.

A manual loop drive crank it is mechanically connected to indicator 25 and its drive shaft til through the connection ii indicated in dotted lines. In the event that manual direction findmg operation is indicated in flight, such as when the electric motor control unit 52 is disconnected or inoperative, direct drive of loop 20 and the associated radio indices 64 and 66 is effected through crank 10. .Aural or visual null signal reception is then used with the system. Crank 10 is normally unclutched from connection II to prevent its rotation during automatic directional operation. An adjusting knob 12 is coupled to bearing scale 13 for displacing it from'its indicated zero position whenever desired during navigation.

In accordance with the present invention, the

control motor drive unit 52 is mounted for read.

electromagnetic clutch unit Wand a reduction g'earingunit 11, forming a mechanically interconnecting integral device. Mechanical cable 53 is detachably connected thereto through fluted same ratiojthat the loop antenna 20 is geared'to just'ed so that indicator 25 shows the proper drive shaft 5L. The angular relation between loop antenna 20 and needle 64 is initially adoutput shaft 18 being held in position by nipple 56 threaded onto threaded projectin tube 59. Metallic prongs project from insulated base 8| at the end'of motor 15, and engage with split metallic receptacle members 82 of socket 83.

' Socket 83 is attached to supporting frame 84 extending from panel'44.

mounted loop was subjected-to.

The mounting of motor drive assembly unit 52 is secured merely by screws 85 extending through gear unit H and engaging with panel 64. The rear of drive assembly 52 is mechanically supported by the four projecting prongs 80 engaged with socket 83. By loosening screws 85, unit 52 including integrally connected motor 15, clutch 16 and gearing 11, is slipped off panel 48. The electrical connections to the motor I and clutch 78 are made through-prongs 80 to electrical cable 81 via socket 83 including its pronged members 82 and connecting lugs 86, as shown in Figs. 3 and 4. Electrical cable 81 and socket 83 remain stationary within the chassis and with respect to internal supporting frame 84. The motor and clutch 16 are accordingly readily electrically disconnected from the circuit when uncoupled in the manner herein set forth.

Figs. 5 and 6 show further details, in crosssection, of motor drive unit 52. The illustrated motor 15 is of the reversible direct current type such as used in the automatic direction finder circuit disclosed in Patent No. 2,308,521 referred to above. It is to be understood, however, that a different type electric motor, such as an alternating current one, may instead be used. Direct current motor 75 has a commutator 88 and brushes 89. Metallic prongs 80 projecting from motor 15 are in suitable electric connection with the brushes and field coils of the motor, as well as with energizing winding 98 of electromagnetic clutch 16.

Suitable electrical connections for the motor 15 and clutch T6 are indicated in Patent No. 2,308,521, as well as in my copending application, Serial No. 346,542 filed on July 20, 1940 now Patent No. 2,267,114 issued Dec. 23, 1941. The electrical cable connection to the motor and clutch therein shown are replaced by prongs 88, in a manner which will now be evident to those skilled in the art. It is to be understood that prongs 80 afford electrical connections for motor 15 and clutch '16 with the electrical control circuits of unit l5 via cable 81. The prongs 88 also impart mechanical support for the motor drive assembly 52, in the manner described hereinabove in connection with Figs. 2 and 3.

The electromagnetic clutch 16 may be of any preferred construction, the illustrated arrangement corresponding to that shown in Patent No. 2,267,114. Clutch 78 comprises a winding 90 generating magnetic flux through drive disk 9! socket members 82 to predetermine the circuit connections of motor unit 52 with the circuits of unit l5.

Although a preferred arrangement of the invention has been described and illustrated, it is of course subject to variation and modification in practice as will be understood by those skilled in the art. It accordingly is not intended to limit the spirit and scope of the invention, except as set forth in the following claims.

What I claim is:

1. A radio direction finder system comprising a rotatable directional antenna, an electric circuit control unit positioned remotely from said antenna, said remote unit containing a reversible electric motor drive mounted therewith, a flexible mechanical shafting having one end connected to the output of said motor drive, a multiple coupling member connected to said shaftand driven disk 92 around a non-magnetic in chassis unit I5 is the normal temperature range it is subjected to during flight conditions. The prior motor drive arrangements were at the loop antenna, and were subjected to the extreme variations in temperaturethat the externally The more normal temperature variations on the motor aiford greater reliability and stability of operation. Furthermore, the motor when placed in imit I5 is far more accessible for'servicing and maingreatly enhances its serviceability. The prongs f .88 of the motor drive unit preferably are mechanically biased or arranged with respect to 7 ing, a quadrantal error corrector coupled with said directional antenna, a plurality of indilow speed output of said gearing, a multiple coupling member connected to said shaft, said member having individual detachable flexible connecting cables extending therefrom, and a plurality of 360 bearing indicators, said indicators and antenna being individually operatively connected with said extending cables in proper relative bearing relation.

3. A radio direction finder system comprising a rotatable directional antenna, a radio and electrical circuit control unit positioned remotely from said antenna and containing an electric motor drive mounted therewith, a flexible mechanical connection between said motor drive and the remotely positioned directional antenna including a 1:1 gearing coupling member having detachable connecting pieces, a quadrantal error corrector between said mechanical connection and said directional antenna, and a plurality of bearing indicators mechanically coupled to said member.

4. A radio direction finder system comprising a rotatable directional antenna, a radio and electrical circuit control unit positioned remotely from said antenna, said remote unit containing a tunable radio portion and an electric motor drive, a tuning control head remote from said unit comprising a movable scale tuning indicator and a rotatable tuning member coupled with said scale, a flexible mechanical shaft connecting said rotatable tuning member with said tunable radio portion for remotely effecting tuning control of the system, separate direction comprising an electric motor, an electromagnetic clutch, reduction gearing, and a plurality of metallic prongs extending from a base of said mo tor drive, said prongs being circuitally connected with electrical components of the motor drive for removably plugging the motor '.drive into said socket in mechanical position on said unit, said socket having coacting elements in circuit with said unit whereby said motor drive is also placed in'predetermined circuital relation therewith.

6. In a radio direction finder system having a rotatable directional antenna and a-radio and electrical control circuit unit remotely positioned from said antenna, a motor drive for said antenna comprising a plurality of conductive mechanical elements secured with the motor, con'- ductive members on said unit in circuit connection with the electrical circuit portion thereof and engageable with said elements, said elements being connected with electrical components of thevmotor and arranged forremovably plugging the motor drive into electrical circuit relation with said unit and into mechanical position therewith, electrical circuit connections between said rotatable antenna and the radio circuit portion of said unit, and a flexible mechanical cable operatively mechanically connecting said antenna with the mechanical output of the re-. .mote removably plugable motor drive.

WILLIAM F. LEAR. 

